I love this type of art and find it super relaxing. No stress about making it look good, I just do it for fun for myself.
Using bic ballpoint pens is almost like sketching with pencil, you can draw light lines or dark lines and create shading. Sometimes I use an alcohol based blender marker over the pen.
After some test pieces I started filling up a sketchbook. Using a thick smooth paper, drawing on both sides.
